PTCR Motor starter Description

PTCR Motor start packages can be economical solid state torque assist for heat pumps, room air, commercial and residential air conditioning and refrigeration systems. PTC thermistors can be used to protect the auxiliary starter winding of induction motors or single phase motors. Compared to the alternative start capacitor and relay, PTCR Motor start devices save several wires, occupy less panel space, mount more easily, and cost less.

PTCR Motor starter Operating Principles

Single phase induction motors (e.g in compressors for refrigerators and air conditioners) can effectively be started when an auxiliary coil is used in the starting phase. The auxiliary coil is cut off from the circuit after the starting phase. For this purpose, PTC thermistor is employed.
When high voltage is applied to the PTC thermistor, the high current causes PTC thermistor to heat up and eventualy the resistance to increase. A high current flows initially (starting phase ) and then decreases in relation to the increase in resistance. After the starting phase, a low residual current flows the auxiliary coil.